scale.score.trans
Class Optimization

java.lang.Object
  scale.score.trans.Optimization

Direct Known Subclasses:

AASR, BasicBlockOps, CP, DeadVarElimination, GlobalVarReplacement, LICM, LoopTrans, Noopt, PRE, ScalarReplacement, SCC, SFIR, TreeHeight, URJ, UselessCopy, ValNum

public abstract class Optimization
extends java.lang.Object

This class is the base class for all optimizations performed on the CFG.

$Id: Optimization.java,v 1.27 2007-10-04 19:58:36 burrill Exp $

Copyright 2008 by the Scale Compiler Group,
Department of Computer Science
University of Massachusetts,
Amherst MA. 01003, USA
All Rights Reserved.

All optimizations applied to the CFG must be defined in this package and must be derived from this class.

Field Summary

protected boolean	dChanged True if CFG nodes added or deleted by the optimization.
static boolean	fpReorder True if floating point operations may be reordered.
static boolean	hasDummyAliases True if there may be aliases between address arguments to subroutines.
static int	IN_SSA The optimization requires that the CFG be in SSA form.
static int	minimumExecutionCost Do not move expressions whose execution cost estimate is less than minimumExecutionCost.
static int	NA_SSA The optimization does not require SSA form or non-SSA form.
static int	NO_SSA The optimization requires that the CFG not be in SSA form.
protected boolean	rChanged True if the variable references are no longer valid.
protected Scribble	scribble The CFG.
static boolean	signedIntsWrapOnOverflow Should signed integers wrap upon overflow?
protected boolean	trace True if the optimization should be traced.
protected UniqueName	un The name generator to use for any variables created.
static boolean	unsafe True if unsafe optimuzations are allowd.
static boolean	unsignedIntsWrapOnOverflow Should unsigned integers wrap upon overflow?
static int	VALID_SSA The optimization requires that the CFG be in SSA form.

Constructor Summary

Optimization(Scribble scribble, java.lang.String tempPrefix)

Method Summary

boolean	assertTrace(boolean trace, java.lang.String msg, boolean val) Print out a trace message to System.out.
boolean	assertTrace(boolean trace, java.lang.String msg, double val) Print out a trace message to System.out.
boolean	assertTrace(boolean trace, java.lang.String msg, long val) Print out a trace message to System.out.
boolean	assertTrace(boolean trace, java.lang.String msg, java.lang.Object o) Print out a trace message to System.out.
boolean	assertTrace(boolean trace, java.lang.String msg, Vector<? extends java.lang.Object> v) Print out a trace message to System.out.
protected VariableDecl	genTemp(Type t) Create a new temporary variable for use by the optimized code.
static int	insertStores(java.util.AbstractCollection<Chord> nodes, Expr lhs, Expr rhs) Insert new copy CFG nodes between CFG nodes in the specified set and CFG nodes that are not in the set but have an edge to them from a node in the set.
abstract void	perform() Perform the optimization.
int	requiresSSA() Return whether this optimization requires that the CFG be in SSA form.
protected boolean	setTrace(boolean classTrace) Sets the trace flag.
static void	sort(java.lang.Object[] v) Place array elements in ascending lexigraphical order by CFG node execution order.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

NO_SSA

public static final int NO_SSA

The optimization requires that the CFG not be in SSA form.

See Also:

Constant Field Values

IN_SSA

public static final int IN_SSA

The optimization requires that the CFG be in SSA form.

See Also:

Constant Field Values

VALID_SSA

public static final int VALID_SSA

The optimization requires that the CFG be in SSA form.

See Also:

Constant Field Values

NA_SSA

public static final int NA_SSA

The optimization does not require SSA form or non-SSA form.

See Also:

Constant Field Values

minimumExecutionCost

public static int minimumExecutionCost

Do not move expressions whose execution cost estimate is less than minimumExecutionCost.

unsafe

public static boolean unsafe

True if unsafe optimuzations are allowd. An unsafe optimization is one that will cause the generated program to be incorrect if there is aliasing.

fpReorder

public static boolean fpReorder

True if floating point operations may be reordered. Reordering floating point operations may result in the generation of slightly different floating point results by the compiled program.

signedIntsWrapOnOverflow

public static boolean signedIntsWrapOnOverflow

Should signed integers wrap upon overflow?

unsignedIntsWrapOnOverflow

public static boolean unsignedIntsWrapOnOverflow

Should unsigned integers wrap upon overflow?

hasDummyAliases

public static boolean hasDummyAliases

True if there may be aliases between address arguments to subroutines.

scribble

protected Scribble scribble

The CFG.

un

protected UniqueName un

The name generator to use for any variables created.

dChanged

protected boolean dChanged

True if CFG nodes added or deleted by the optimization.

rChanged

protected boolean rChanged

True if the variable references are no longer valid.

trace

protected boolean trace

True if the optimization should be traced.

Constructor Detail

Optimization

public Optimization(Scribble scribble,
                    java.lang.String tempPrefix)

Parameters:

scribble - is the CFG to be transformed

tempPrefix - is used to generate temporary variable names

Method Detail

setTrace

protected boolean setTrace(boolean classTrace)

Sets the trace flag.

genTemp

protected VariableDecl genTemp(Type t)

Create a new temporary variable for use by the optimized code. The variable definition is added to the set of variables for this CFG.

perform

public abstract void perform()

Perform the optimization. Each optimization must specify

• if the CFG is left in valid SSA form
• if the dominance information is still valid
• if the variable reference information is still valid

after it completes. The Scribble class provides methods that may be used to sepcify this information.

requiresSSA

public int requiresSSA()

Return whether this optimization requires that the CFG be in SSA form. It returns either

NO_SSA

the CFG must not be in SSA form,

IN_SSA

the CFG must be in SSA form,

VALID_SSA

the CFG must be in valid SSA form, or

NA_SSA

the CFG does not need to be in valid SSA form.

sort

public static void sort(java.lang.Object[] v)

Place array elements in ascending lexigraphical order by CFG node execution order.

Parameters:

v - is an array of CFG nodes or expressions

See Also:

Chord.pushChordWhenReady(scale.common.Stack, int)

insertStores

public static int insertStores(java.util.AbstractCollection<Chord> nodes,
                               Expr lhs,
                               Expr rhs)

Insert new copy CFG nodes between CFG nodes in the specified set and CFG nodes that are not in the set but have an edge to them from a node in the set.

Parameters:

nodes - is the set of CFG nodes

lhs - is the left hand side for new CFG nodes

rhs - is the right hand side for new CFG nodes

Returns:

the number of new CFG nodes added

assertTrace

public final boolean assertTrace(boolean trace,
                                 java.lang.String msg,
                                 java.lang.Object o)

Print out a trace message to System.out. This method is meant to be used in an assert statement.

Parameters:

msg - is the message

o - is an object to append to the message

Returns:

true

assertTrace

public final boolean assertTrace(boolean trace,
                                 java.lang.String msg,
                                 long val)

Print out a trace message to System.out. This method is meant to be used in an assert statement.

Parameters:

msg - is the message

val - is an integer to append to the message

Returns:

true

assertTrace

public final boolean assertTrace(boolean trace,
                                 java.lang.String msg,
                                 double val)

Print out a trace message to System.out. This method is meant to be used in an assert statement.

Parameters:

msg - is the message

val - is an integer to append to the message

Returns:

true

assertTrace

public final boolean assertTrace(boolean trace,
                                 java.lang.String msg,
                                 boolean val)

Print out a trace message to System.out. This method is meant to be used in an assert statement.

Parameters:

msg - is the message

val - is an integer to append to the message

Returns:

true

assertTrace

public final boolean assertTrace(boolean trace,
                                 java.lang.String msg,
                                 Vector<? extends java.lang.Object> v)

Print out a trace message to System.out. This method is meant to be used in an assert statement.

Parameters:

msg - is the message

v - is a vector of things to display

Returns:

true